DAKAR/HAVANA, July 15 (Reuters) - The death toll from the world's worst ever Ebola outbreak in West Africa has risen to 603 since February, with at least 68 deaths reported from three countries in the region in the last week alone, the World Health Organization said on Tuesday. WHO said there were 85 new cases between July 8-12, highlighting continued high levels of transmission. International and local medics were struggling to get access to communities as many people feared outsiders were spreading rather than fighting Ebola. "It's very difficult for us to get into communities where there is hostility to outsiders," WHO spokesman Dan Epstein told a news briefing in Geneva. "We still face rumors, and suspicion and hostility ... People are isolated, they're afraid, they're scared." Sierra Leone recorded the highest number of deaths, which include confirmed, probable and suspect cases of Ebola, with 52. Liberia reported 13 and Guinea 3, according to the WHO figures. Epstein said the main focus in the three countries is tracing people who have been exposed to others with Ebola and monitoring them for the 21-day incubation period to see if they were infected. "It's probably going to be several months before we are able to get a grip on this epidemic," Epstein added. Ebola causes fever, vomiting, bleeding and diarrhea and was first detected in then Zaire, now Democratic Republic of Congo, in the mid-1970s. Spread through contact with blood and body fluids of infected people or animals, it is one of the world's deadliest viruses, killing up to 90 percent of those infected. Speaking from Havana, WHO Director-General Margaret Chan called the outbreak the world's worst ever by number of cases, saying, "The situation is serious but not out of control yet." The WHO was mobilizing political, religious and local leaders in Sierra Leone, Liberia and Guinea to create a better welcome for medical professionals attempting to treat victims, Chan said, while also coordinating responses from the three affected countries and eight neighbors that have experienced Ebola. "Sometimes the challenge for us is countries like to do disease control their way. But I think this is one such situation where countries must come together and adopt a similar approach to deal with a very dangerous disease," Chan said. The organization was also consulting with anthropologies to help suspend local customs such as eating bush meat or hugging and kissing Ebola victims at their funerals, which can transmit the disease, Chan said. The outbreak started in Guinea's remote southeast but has spread across the region's porous borders despite aid workers scrambling to help some of the world's weakest health systems tackle a deadly, infectious disease. In Sierra Leone and Guinea, experts believe scores of patients are being hidden as relatives and friends believe hospitalization is a "death sentence". In Liberia, health workers have been chased away by armed gangs. (Reporting by David Lewis and Daniel Trotta; Editing by Bate Felix, Ralph Boulton and Bernard Orr)